First of all, because of honestly silly reasons, in CESM so4_a2 is Aitken and so4_a1 is Accumulation mode.
Also, the quantities are in kg of SO4 (or SO2) per m2, so they need to be divided by 3 (or 2). If you do that, then the numbers should be the same as the ones I had in my slides that i calculated (going by memory, but I'll check tomorrow morning to be sure), which should be reasonable considering a lifetime of around 13-14 months (and higher for H2SO4 injections)

TMSO2     SO2 total mass
TMso4_a1  accumulation mode total mass
TMso4_a2  Aitken mode total mass
TMso4_a3  coarse mode total mass
